.back_box {
  width: 100vw;
  height: 56.25vw;
  overflow: hidden;
}

.background_his {
  background: url('../img/background.png');
  background-size: 100% 100%;
  transition: background 1s;
}

.background_point {
  background: url('../img/packground_point.png');
  background-size: 100% 100%;
  transition: background 1s;
}

.background_plan{
  background: url('../img/plan_back.png');
  background-size: 100% 100%;
  transition: background 1s;
}